The ultimate deficiency thread

[MrG]

Ladies and gents I came across an excellent read so thought I'd copy it to here.
Its a mighty read with lots of pics and should get you out of any trouble regarding deficiencies.
I'll be doing this on a def per post basis so please bear with me.


Cannabis Plant Problems & Symptoms | Marijuana Nutrient Deficiencies
Many weed plant problems can be fixed by getting a good nutrient system that is formulated for plants like the tomato. The key thing is that the nutrients need to come with a different nutrient schedule for the "vegetative" and "flowering" stage, just like marijuana plants.

And remember that maintaining a proper pH will prevent a bunch of nutrient deficiencies, because the roots can only access the nutrients if the pH is in the correct range.

How do I check the pH and how's it related to marijuana nutrient deficiencies anyway?

If you're growing in soil, aim for a root pH between 6.5 - 7.0. In hydroponic marijuana grows (including growing in inert mediums like coco coir), aim for a root pH between 5.5-6.5.

View pictures and descriptions below of all the common marijuana nutrient deficiencies and other weed plant problems.

Boron Deficiency
Problem: A boron deficiency in cannabis is relatively rare, and is usually accompanied by other types of nutrient or pH problems.

The first signs of a cannabis boron deficiency is abnormal or thick growth tips along with brown spotting on new leaves.



With a boron deficiency, upper cannabis leaves display abnormal and/or slowed growth. Growing tips may not grow properly, may display twisted growth, and may die off. New leaves may wrinkle or curl.

Plant roots can also be affected by a boron deficiency, showing unhealthy or slow growth. Stems may become rough or hollow.

A plant with a boron deficiency may look like it has a calcium deficiency because boron is needed for the plant to properly use calcium. New growth is affected the most, and may look like it's been burnt or scorched.

A boron deficiency is often accompanied by an apparent potassium or nitrogen deficiency, as these nutrients are needed for the plant to use boron. Boron deficiencies are more likely to appear when a plant is underwatered or experiencing very low humidity (very dry air).

*

Solution for Boron Deficiency in Cannabis

Your plant may also exhibit signs of a boron deficiency if the pH is too high or low. Learn how to manage your pH when growing cannabis.

In soil, boron is best absorbed by the roots in the 6.0 - 7.0 pH range.

In hydro, boron is best absorbed by the roots in the 5.5 - 6.2 pH range (in hydro, it's generally recommended to keep the pH between 5.5 - 6.5, but boron specifically tends to be best absorbed below 6.2).

Boron is not absorbed well by cannabis without enough potassium and nitrogen, or if there isn't enough moisture (for example if plant is underwatered or humidity is too low). That's why it is recommended you water your plant with a regular dose of nutrients below.

A plant is more likely to show signs of boron deficiency when the humidity is very low (below 25% relative humidity in the air), so you may help humidifier may be needed if your grow room is very dry.

Please note: Boron deficiencies are more likely to happen when a grower is using heavily filtered or reverse osmisis (RO) water to feed plants, since boron is found in most tap water.

If you suspect your growing cannabis plant has a boron deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients. Old damaged growth will likely not recover. Watch plant over next few days to make sure that the problem stops spreading to new growth.


Leaf Color:*
Edges Appear Brown or Burnt
Pale Color Leaves
Dark or Purple Leaves
Brown or Dark Spots
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Thick Growth Tips
Spots
Slow Growth
Twisted Growth
Abnormal Growth
Plant Symptoms:*
Slow Growth
Twisted Growth
Root Symptoms:*
Slow Growing

Cont.

[MrG]

Calcium Deficiency

Problem: Calcium is an important nutrient which helps provide structure to the cannabis plant and helps it withstand stress like from heat.


A cannabis calcium deficiency can sometimes be difficult to diagnose since calcium deficiencies are often accompanied by magnesium, iron, and/or other deficiencies.

Calcium moves relatively slowly through the plant (it is a semi-mobile nutrient), and tends to remain concentrated in older growth. Calcium deficiencies tend to show up in newer growth (upper leaves).



Calcium Deficiencies Appear Near Top of Plant

Calcium deficiencies tend to appear on newer growth, which means it first appears on the leaves towards the top of the plant.

Some of the most noticeable signs of a calcium deficiency will appear on new, upper leaves which may display:

Dead spots
Crinkling
Spotting / Mottling
Small brown spots
Stunted growth
Small or distorted new leaves
Curled tips
Leaf die-off
Affected leaves may appear dark green

Here's a close-up of a calcium deficiency that appeared on leaves towards the top of a cannabis plant grown in coco coir:



Other Symptoms of Calcium Deficiency

If a cannabis plant is affected by a calcium deficiency for too long, it may begin to show the following symptoms due to the lack of calcium.

Stems become weak or flimsy and may crack easily
Stems become hollow or show inner signs of decay
Plant does not stand up well to heat
Flowers/buds do not develop fully, or development is slow
Roots appear weak or under-developed
In severe calcium deficiencies, parts of roots may even die off or turn brown
Roots are more susceptible to root problems like slimy root rot
Cannabis tends to like high levels of calcium, so it is unusual to feed too much calcium when using normal amounts of nutrients and/or regular soil. There are not many known cases of cannabis calcium toxicity (too much calcium), however too much calcium can cause the plant to lock out other nutrients, so it's important not to go overboard..

Calcium deficiencies are more likely to appear when...

Grower is using filtered or reverse osmisis (RO) water to feed plants - the amount of calcium found in tap water varies, but some tap water has enough calcium to prevent calcium deficiencies
Growing cannabis in hydroponics with nutrients that don't supplement calcium or when growing in water that has less than 6.2 pH
Growing cannabis in coco coir that hasn't been supplemented with calcium or below 6.2 pH
When growing in soil or soilless growing medium that hasn't been supplemented with calcium (usually from dolomite lime) or is acidic (below 6.2 pH)
Too much potassium can also sometimes cause the appearance of a calcium deficiency
Outdoors - calcium deficiency is more likely to appear in acidic soil (below 6.2 pH)


Different strains of cannabis tend to have different nutrient problems. Some cannabis strains (or even specific plants) tend to use much higher levels of calcium than others, and so you may see calcium deficiency problems with one plant even when all the other plants (which are getting the same nutrients and environment) aren't showing any signs of deficiency.

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Solution For Calcium Deficiency in Cannabis

Your cannabis plant may show signs of a calcium deficiency if the pH at the roots is too high or too low. That is* because when the pH of your root zone is off, your cannabis cannot properly absorb calcium through its roots. Therefore the first step is to ensure that you have the correct pH for your growth medium. Learn more about pH and cannabis.

Please note: After a calcium deficiency is cleared up, the problem (brown spots and unhealthy new leaves) will stop appearing on new growth, usually within a week. Please note that leaves which have been damaged by a calcium deficiency will probably not recover or turn green, so you want to pay attention to new growth for signs of recovery.

In soil, calcium is best absorbed by the roots in the 6.2 - 7.0 pH range (in soil, it's generally recommended to keep the pH between 6.0 - 7.0, but calcium specifically tends to be best absorbed above 6.2)
*
In hydro, calcium is best absorbed by the roots in the 6.2 - 6.5 pH range (in hydro, it's generally recommended to keep the pH between 5.5 - 6.5, but calcium specifically tends to be best absorbed above 6.2)
*
If you suspect your growing cannabis plant has a calcium deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes calcium. This will remove any nutrient salts that may be affected the uptake of calcium and help restore pH to the proper levels..

To supplement with extra Calcium... (it's very rare to give a cannabis plant too much calcium, however, too much calcium can lock out other nutrients so don't go overboard)

Calcium, magnesium, and iron deficiencies often appear together in cannabis. Many growers decide to purchase some sort of Calcium-Magnesium (often called Cal-Mag) supplement for their grow room in case this common deficiency appears.

Listed below are common cannabis Calcium supplements, along below with some general information about each one. After supplementing with Cal-Mag and correcting the pH, you should expect to see new healthy growth within a week. Remember, the old leaves will probably not recover, but new growth should be green and healthy.

Cal-Mag is Well Suited For Hydro, Coco Coir, or Soil



Botanicare Cal-Mag Plus is a calcium, magnesium, and iron plant nutrient supplement. General application is to mix 1 tsp (5ml) of Cal-Mag into each gallon of water. I have used Cal-Mag Plus several times with great results.

Guaranteed Analysis: Nitrogen (N) 2.0%, Calcium (Ca) 3.2%, Magnesium (Mg) 1.2%, Iron (Fe) 0.1%

Derived from: Calcium Nitrate, Magnesium Nitrate, Iron EDTA
*

*

Dolomite Lime - For Soil Growers (Organic)

If you're looking for a way to supplement calcium in your organic or soil setup, I highly recommend a product called "Dolomite Lime."

Dolomite is a good source of calcium and magnesium and can be mixed with your soil. The great thing about dolomite is it works slowly over the course of a few months.

Dolomite has a neutral pH of about 7.0 and will help keep soil at the correct neutral pH range which is optimum for cannabis growth.

You can buy Dolomite Lime online, but with shipping it's almost always waaaay cheaper to pick up a bag at a home improvement or gardening stores, gardening centers, etc.* If possible, try to get a finer grade of dolomite compared to something that is more coarse.

How to Use Dolomite Lime for Cannabis: When growing cannabis indoors, add 6-7 teaspoons of fine dolomite lime to each gallon's worth of soil. So if you're mixing enough soil to fill a 5 gallon container, you want to add 30-35 teaspoons (about 2/3 cup) of dolomite lime to the mix. Mix the dolomite lime and the dry soil thoroughly, then lightly water it with water that has been pH'ed to 6.5. After getting the soil wet, mix the soil well and wait a day or two to let the soil settle before checking the pH and adding plants. When growing in an outdoor garden, follow the dolomite lime manufacturers instructions.

Leaf Color:*
Brown or Dark Spots
Mottling / Mosaic Pattern
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Leaf Edges Appear Burnt
Leaf Tips Appear Burnt
Leaf Tips Die
Spots
Mottling / Mosaic
Slow Growth
Twisted Growth
Abnormal Growth
Plant Symptoms:*
Weak Stems
Slow Growth
Twisted Growth
Root Symptoms:*
Brown
Slow Growing
Other Symptoms:*
Buds Not Fattening

Cont.

[MrG]

Copper Deficiency
Problem: A cannabis copper deficiency is rare and manifests itself as leaves curling back, lack of growth, and unusual dark coloring of the leaves. Copper doesn't move easily through the plant and is considered "low-mobile."

Symptoms of New (Young) Leaves

Dark or twisted
Purple or blue undertones
Metallic sheen on leaves
Leaves turn under
Tips may turn yellow or white
Symptoms of Older Leaves

Older leaves may show signs of pale yellow or white
Other Copper Deficiency Symptoms

Buds do not ripen, or grow very slowly
Pistils (hairs) on female plants may not grow properly
Plant may wilt or have limp leaves
New growth has difficulty opening up
It is very unlikely that there is no copper available in your water or soil, so usually a copper deficiency in cannabis is caused by a pH problem at the roots that is restricting access to nutrients.

Often it is a problem with another nutrient or with the pH that causes the appearance of a copper deficiency.



Copper toxicity (too much copper) in cannabis plants is rare, though a severe case of too much copper can cause a quick death to the plant.
*

Solution For Cannabis Copper Deficiency

If you suspect your growing cannabis plant has a copper deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients. This will remove any nutrient salts that may be affected the uptake of copper and help restore pH to the proper levels..

Watch to make sure that the problem starts to clear up within a couple of days. Old growth may not recover, but new growth should be healthy.

In soil, copper is best absorbed by the roots in the 6.0 - 7.0 pH range
*
In hydro, copper is best absorbed by the roots in the 5.5 - 6.5 pH range
If you cannot get rid of a cannabis copper deficiency.

Leaf Color:*
Pale Color Leaves
Yellow Leaves - Lower, older leaves
Dark or Purple Leaves
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Lower Leaves / Older Growth Affected
Slow Growth
Twisted Growth
Abnormal Growth
Leaves Curl Under
Wilting / Drooping
Plant Symptoms:*
Weak Stems
Slow Growth
Twisted Growth
Leaves Curl Under
Plant Wilting / Drooping

Cont.

[MrG]

Heat Stress

Problem: Your cannabis plant can only withstand a certain amount of heat and light. After a certain point, your cannabis will start exhibiting signs of stress on the leaves near the sources of light and/or heat. Your leaves will get yellow or brown brown spotting and may appear generally burnt in places when there's too much light.

Important for Hydroponic Growers!*High temps can trigger*root rot, a serious problem that can kill your plants.

Cannabis will also display heat stress when grown outdoors in hot, dry weather, especially when not given enough water.


When the heat gets too high, the edges of the leaves will begin to curl up and the leaves will begin to "cup."

Heat Stress


Heat stress is even more damaging in the flowering stage since plant is no longer growing many new leaves. Indica-leaning strains are most prone to heat damage in the flowering stage. Heat damage during budding will reduce your yields by demolishing many of your most important leaves, while also causing buds to grow airy with ugly*foxtails.

Even though the grow lights were turned off, this is what happened to an indica-leaning plant overnight after being exposed to 105°F (40°C) temperatures during a heat wave.


Heat during the flowering stage also causes fox-tails, which are airy and don't have much substance to them. The plant is basically "abandoning" the original heat-damaged bud to try to make a sad new one.

Example of unwanted "fox-tailing" caused by too-much heat

*

Solution: Get a way to monitor*temperature.*Control heat by whatever means necessary using the steps outlined below.
*

Indoors, find a way to lower the temperature and/or increase the circulation in the grow room or grow area if heat is the problem. Having a small fan blowing over the tops of your plants will help prevent hot spots from forming directly under your grow lights.

You may consider removing grow lights further away from the tops of the plants if heat is a problem.

When learning how to grow cannabis, it's best to try to keep things at a comfortable room temperature at all times for optimal growth. If it's too hot for you, it's probably too hot for your plants.



When cannabis plants are recovering from*heat shock, some growers recommend using*seaweed kelp extract (often available as a convenient*liquid fertilizer) to help plants recover from the stress and possible even*protect*plants from heat stress in the future.
Many indoor setups will require that you*vent out hot air using a fan and/or an*exhaust system. By creating*good suction with an efficient exhaust system*and adding a carbon scrubber, you can also pretty much scrub*all smells from the grow room.

An oscillating fan will circulate air in the room as well as provide a gentle breeze for your plants, and a small one will cost less than £20.


Outdoors, you have less options to reduce heat during a heat wave, but you are able to monitor your local weather via weather forecasts.

It is possible to partially shield your plants when you know the temperature is going to get hot. You can also adjust your watering schedule to make sure plants at least have plenty of water.

Some things to try when you know the weather outside*is going to be hot or dry:

water plants in the evening or early morning*to help prevent water evaporation during the hottest hours

kelp extract for roots*-*provide a small amount of liquid fertilizer that contains seaweed kelp extract (can help protect against heat stress)

increase shade*to reduce the heat experienced by plants*- you can use an old sheet or other cloth as a short term solution, or get a profesionally made "Sun Shade Sail" which is made particularly to create shade outdoors. It's important to remember that giving plants shade for more than a few days will make them less "hardened" to the sun, and you may need to reintroduce full sunlight back slowly to prevent them from getting shocked from the light intensity

move potted plants*- luckily with potted plants, it's usually easier to move them out of direct sunlight during a heat wave

take extra good care of heat-stressed plants*-*when cannabis plants appear*heat-stressed, try to baby them*as best you can, and offer shade during the hottest days.

When growing cannabis outdoors, it can often take a few weeks for plant to recover after a hot or dry spell, so prevention is the best medicine for outdoor plants.

Cont.

[MrG]

Iron Deficiency

Problem:* An iron deficiency in cannabis is relatively rare, and the symtpoms of a cannabis iron deficiency appear most often alongside other nutrient problems or deficiencies.

The main symptoms of an iron deficiency are:

Yellowing of upper fan leaves
Yellowing of smaller inner leaves
Veins of leaves stay green
Sometimes affected leaves will even appear white. Often the symptoms appear near the top of the plant on newer leaves.

With an iron deficiency, the veins of the leaves will tend to stay green even while the rest of the leaf is completely yellow.

This nutrient deficiency can look similar to a*magnesium deficiency, but an iron deficiency will affect younger/upper/inner leaves (where a magnesium deficiency affects older/lower leaves).


The following severe iron deficiency was actually caused by an outdoor grower using too much pure chicken manure as a fertilizer. Any time you use manure to fertilize your plants, remember a little bit goes a long way! Chicken manure tends to raise the pH of soil, which is one of the prime causes of an iron deficiency. In addition to changing the pH, the high level of nutrients contained in chicken manure may have interfered with iron uptake by the roots, causing further iron lock-out.


Immediately after adding chicken manure and watering, the plant started producing bright yellow, almost white leaves that immediately dried up and died. Even though this plant was showing the signs of an iron deficiency, the iron was available in the soil - the problem was that the plant just couldn't get access to the nutrients due to nutrient lock-out conditions. In this case, grower needs to dig up the manure (since that is the real cause of this problem) & replant with good soil.

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Solution For Cannabis Iron Deficiency

Iron tends to get locked at at higher pH levels, especially when the pH at the roots is above 7.0, and more commonly in soil than in hydro.

Iron can also react with other nutrients, causing other nutrient lock-outs at the same time. If you are supplementing with iron, make sure you read the label to minimize any problems or interactions with your current nutrient system.

If you suspect your growing cannabis plant has a iron deficiency due to too-high pH, flush your system with clean, pH'd water. This will remove any nutrient salts that may be affecting the uptake of iron and help restore pH to the proper levels..

In soil, iron is best absorbed by the roots in the 6.0 - 7.0 pH range (iron tends to get locked out when the pH is above 7.0, and if you suspect an iron deficieny, you may wan to consider lowering your root pH to ~6.5 just to be safe)
*
In hydro, iron is best absorbed by the roots in the 5.5 - 6.5 pH range
Watch to make sure that the problem starts to clear up within a couple of days to a week, since iron moves relatively slowly through the plant.

After correcting the cause of an iron deficiency (usually too-high pH), you should expect to see new healthy growth within a week. Remember, the old leaves will probably not recover, but new growth should be green and healthy, without the yellowing of new leaves as you were seeing with the iron deficiency..

If you suspect you have a iron deficiency even though the pH is correct, flush your system with clean, pH'd water (if on schedule, you can do this alongside a dose of your regular nutrients) and add a supplement that contains Iron, Calcium and Magnesium.

Iron deficiencies often appear alongside deficiencies with calcium and magnesium, or an excess of copper. Many growers decide to purchase some sort of Calcium-Magnesium (often called Cal-Mag) supplement for their grow room in case one these deficiencies appear.

If you think you need to supplement with extra iron, a product known as Cal-Mag is suited for Hydro, Coco Coir, or Soil (not organic, though). This is a great choice because it also contains extra calcium and magnesium, which are deficiencies that often happen alongside an iron deficiency.

Botanicare Cal-Mag Plus is a calcium, magnesium, and iron plant nutrient supplement. General application is to mix 1 tsp (5ml) of Cal-Mag into each gallon of water.

Guaranteed Analysis: Nitrogen (N) 2.0%, Calcium (Ca) 3.2%, Magnesium (Mg) 1.2%, Iron (Fe) 0.1%

Derived from: Calcium Nitrate, Magnesium Nitrate, Iron EDTA

Watch to make sure that the problem starts to clear up within a couple of days to a week, since iron moves relatively slowly through the plant. Old growth may not recover, but new growth should be healthy.


Leaf Color:*
Pale Color Leaves
Yellow Leaves - New Growth
Yellowing Between Veins
Veins of Leaves Stay Green
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Small Inner Leaves Affected
Leaf Tips Die
Yellowing Between Veins
Veins of Leaves Stay Green
Abnormal Growth.

Cont.

[MrG]

Light Burn
Problem: Your cannabis plant can only withstand a certain amount of heat and light. After a certain point, your cannabis will start exhibiting signs of stress on the leaves near the sources of light and/or heat. Your leaves will get yellow or brown brown spotting and may appear generally burnt in places when there's too much light.

If you directly touch a plant's leaves with the lights, you will also leave "burns" if the bulbs were hot when they touched the leaves.

When the heat gets too high, the edges of the serrated leaves will begin to curl up even if there are no burns or other signs of light stress.

Light Burn


Light stress often first appears around the edges of leaves


This cannabis seedling basically grew up into the grow light!


This cannabis seedling is being burned by too-close LED grow lights


Cont.

[MrG]

Light Bleaching

Light bleaching is most common with high-power LEDs, but can also happen to highly-ventilated HPS lights that are kept too close to the tops of the plants. Basically, this is what happens when plants get too much light, kinda like how hair on top of your head can turn lighter if you spend plenty of time in the sun.


Buds which have been bleached tend to be low potency or even have no potency (no available THC or other cannabinoids). Therefore you should avoid light-bleaching your plants at all costs!



Sometimes light-bleached cannabis will get mis-labeled as “albino cannabis” or “white cannabis” but the truth is that the white color is not healthy, so this is not a desirable trait (even if it looks pretty cool).

Solution: If your marijuana plants are getting too much light, try removing some of the lights or moving your grow lights further away from the tops of the plants.

It is unlikely for your plants to get "light-burned" from the sun when growing outdoors, and they definitely can't accidentally grow into the sun. Outdoor plants can show signs of light stress if plants were*used to shady conditions and moved into direct sunlight without time to get accustomed*to the brigher light levels.

When making changes to your plant's environment, it's best to make changes slowly if possible. Slow gradual changes are best for preventing stress when*growing indoors or outdoors.

Sometimes heat stress can look like light*stress. When learning how to grow cannabis, it's best to try to keep things at a comfortable temperature at all times for optimal growth. If it's too hot for you, it's probably too hot for your plants. Outdoors, things can be a bit harder, but there are steps you can take to protect your outdoor plants from the heat.*Learn more about cannabis heat stress.

*

Leaf Color:*
Edges Appear Brown or Burnt
Pale Color Leaves
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Leaf Edges Appear Burnt
Leaves Curl Upwards
Wilting / Drooping
Plant Symptoms:*
Leaves Curl Upwards
Plant Wilting / Drooping

Cont.

[MrG]

Magnesium Deficiency

Problem: A light green or yellow coloring will begin to show on the veins and edges of the lower & older leaves - this is one of the classic signs of cannabis magnesium deficiency.

Magnesium is a mobile nutrient, which means that the plant can move it from old leaves to new leaves.*

If you don't react to it promptly,*a cannabis magnesium defiency can spiral out of control*and cause your plant to lose a lot of lower leaves quickly. The plant will pull magnesium out of older leaves and bring them to the newer leaves. That's why a magnesium deficiency usually appears towards the bottom of the plant and on older, less important leaves.

The edges of the leaves may become yellow or bright green and may start feeling crispy to the touch.*This crispiness around the edges*is different from nutrient burn, which*does not lighten the margins inside the leaves.

Sometimes you will also get light brown spotting within the margins or along the edges if the problem continues to get worse, though this may be partially other deficiencies,*which often happen*alongside a magnesium defiency.

Magnesium deficiencies are easy to prevent and fix once you know what to do. Read on below to learn how.


Solution For Magnesium Deficiency in Cannabis

Your cannabis plant may show signs of a magnesium deficiency if the pH at the roots is too low, especially in hydro. That is because when the pH of your root zone is not in the correct range, your cannabis cannot properly absorb magnesium through the roots.

Often with this deficiency, the magnesium is present, but the roots cannot absorb the magnesium properly due to an improper pH. Therefore it is very important to maintain the correct pH (and make sure the pH does get to low / acidic) in order to avoid a magnesium deficiency.

Growers using Coco Coir or Reverse Osmosis (RO) water usually need to supplement their plants*with extra Calcium & Magnesium in addition to regular nutrients. Treating coco coir with Cal-Mag and supplying extra throughout your grow is recommended for grower in coco coir, or those using RO water.


Adding more magnesium to a system when there is a pH lock-out will probably not help because the plant will not be able to absorb any magnesium until the pH has been corrected. If there's already enough magnesium, adding more*can*cause other apparent deficiencies by locking out other nutrients from the plant.

Please note: Once a magneisum deficiency is cleared up, the problem (yellowing lower leaves) will stop spreading to other older leaves, usually within a few days. Please note that leaves which have been damaged by a magnesium deficiency will probably not recover or turn green, so you want to pay attention to other growth for signs of recovery.

In soil, magnesium is best absorbed by the roots in the 6.0 - 7.0 pH range (some growers say a 6.5 - 7.0 pH is best if you suspect a magnesium deficiency)
*
In hydro, magnesium is best absorbed by the roots in the 6.0 - 6.5 pH range (in hydro, it's generally recommended to keep the pH between 5.5 - 6.5, but magnesium specifically tends to be best absorbed above 6.0)
If you suspect your growing cannabis plant has a magnesium deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes magnesium. This will remove any nutrient salts that may be affected the uptake of magnesium and help restore pH to the proper levels..

To supplement with extra Magnesium...

Calcium, magnesium, and iron deficiencies often appear together in cannabis. Many growers decide to purchase some sort of Calcium-Magnesium (often called Cal-Mag) supplement for their grow room in case this common deficiency appears.

Listed below are common cannabis Calcium supplements, along below with some general information about each one. After supplementing with Cal-Mag and correcting the pH, you should expect to see new healthy growth within a week. Remember, the old leaves will probably not recover, but new growth should be green and healthy.

Cal-Mag is Well Suited For Hydro, Coco Coir, or Soil



Botanicare Cal-Mag Plus is a calcium, magnesium, and iron plant nutrient supplement. General application is to mix 1 tsp (5ml) of Cal-Mag into each gallon of water. I have used Cal-Mag Plus several times with great results.

Guaranteed Analysis: Nitrogen (N) 2.0%, Calcium (Ca) 3.2%, Magnesium (Mg) 1.2%, Iron (Fe) 0.1%

Derived from: Calcium Nitrate, Magnesium Nitrate, Iron EDTA

*

*

Dolomite Lime - For Soil Growers (Organic)

If you're looking for a way to supplement magnesium in your organic or soil setup, I highly recommend a product called "Dolomite Lime."

Note: The finer the dolomite, the more quickly it will be available to nutrients

Dolomite is a good source of calcium and magnesium and can be mixed with your soil. The great thing about dolomite is it works slowly over the course of a few months.

Dolomite has a neutral pH of about 7.0 and will help buffer pH in soil so it's easier to maintain the correct neutral pH range which is optimum for cannabis growth, especially in acidic soils.

You can buy Dolomite Lime online, but with shipping it's almost always waaaay cheaper to pick up a bag at a home improvement or gardening store such as Lowes, Home Depot, gardening centers, etc.* If possible, try to get a finer grade of dolomite compared to something that is more coarse.

How to Use Dolomite Lime for Cannabis: When growing cannabis indoors, add 6-7 teaspoons of fine dolomite lime to each gallon's worth of soil. So if you're mixing enough soil to fill a 5 gallon container, you want to add 30-35 teaspoons (about 2/3 cup) of dolomite lime to the mix. Mix the dolomite lime and the dry soil thoroughly, then lightly water it with water that has been pH'ed to 6.5. After getting the soil wet, mix the soil well and wait a day or two to let the soil settle before checking the pH and adding plants. When growing in an outdoor garden, follow the dolomite lime manufacturers instructions.

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*

Hand-watered grow - Flush the system with properly pH'ed water that contains a full set of proper nutrients that are suitable for growing cannabis. Make sure you are using the right nutrients for the stage your plant is in. Check the pH of your runoff water to ensure that nothing in the growing medium is throwing off the root pH.

Hydro grow - Check the pH and PPM of your reservoir water to make sure that pH is on target and nutrient levels are not lower than expected. If you do this and are still not certain what is causing the magnesium defiency, it is recommended that you drain your reservoir and refill with a newly mixed reservoir with fresh nutrients that has been pH'ed.

Should I add extra Magnesium? Some growers will add*1 tsp of Epsom salt/gallon of water and water plants with this mixture in response to a magnesium defiency (since epsom salt is primarily made of magnesium).

As I mentioned, often a magnesium deficiency is actually caused by a mix of factors, such as pH being off. Even if the pH is on target, sometimes a magnesium defiency appears when other important nutrients like iron or calcium are not present in the right quantities.

A great supplement that has all of 3 of these important nutrients is known as Cal-Mag, as this contains Magnesium and Calcium, as well as a trace amount of iron.

Adding extra magnesium is often not necessary if you are using tap water. However, you will likely want to supplement Cal-Mag if you are using filtered or reverse osmosis (RO) water, since most tap water already contains some amount of all 3 of these cannabis nutrients. Cal-Mag also has a small amount or iron, which is another trace cannabis nutrient that is often missing in filtered water.

How long until new growth looks better? If you fix the root of the problem, further yellowing and discoloration of the leaves should stop almost immediately. Some of the effected leaves may recover somewhat, but what's most important is to make sure the problem isn't continuing to spread to other leaves on the plant.

I generally don't remove any discolored leaves until I know for sure that the problem is completely gone and is no longer spreading to new leaves (that way any possible further discoloration will happen to the leaves that have already been affected).

*

Leaf Color:*
Edges Appear Brown or Burnt
Pale Color Leaves
Yellow Leaves - Lower, older leaves
Yellowing Between Veins
Veins of Leaves Stay Green
Brown or Dark Spots
Mottling / Mosaic Pattern
Leaf Symptoms:*
Lower Leaves / Older Growth Affected
Leaf Tips Appear Burnt
Leaf Tips Die
Yellowing Between Veins
Veins of Leaves Stay Green
Spots
Mottling / Mosaic
Old Leaves Dropping Off
Twisted Growth
Leaves Curl Under
Leaves Curl Upwards
Wilting / Drooping
Plant Symptoms:*
Old Leaves Dropping Off
Twisted Growth
Leaves Curl Under
Leaves Curl Upwards
Plant Wilting / Drooping

Cont.

[MrG]

Manganese Deficiency

Problem: Leaves may become yellow in between the veins, with mottled brown spots on the affected leaves. These brown dead patches may spread and eventually kill the leaf. Leaves may also shred and fall apart.

Overall growth of the marijuana plant may be stunted. With a manganese deficiency, the yellowing will begin at the base of the leave and move outwards towards the tips.

*

Solution for Manganese Deficiency in Cannabis

Your plant may also exhibit signs of a manganese deficiency if the pH is too high, or if the plant is getting too much iron.

Learn how to manage your pH when growing cannabis.

Please note: After a manganese deficiency is cleared up, the problem (brown spots and yellowing leaves) will stop spreading to other growth usually within a week. Please note that leaves which have been damaged by a manganese deficiency will probably not recover or turn green, so you want to pay attention to other growth for signs of recovery.

In soil, calcium is best absorbed by the roots in the 6.0 - 7.0 pH range (some growers recommend keeping the pH slightly lower, from 6.0 - 6.5, if you suspect a manganese deficiency in particular)
*
In hydro, calcium is best absorbed by the roots in the 5.5 - 5.8 pH range (in hydro, it's generally recommended to keep the pH between 5.5 - 6.5, but manganese specifically tends to be best absorbed below 5.8)
If you suspect your growing cannabis plant has a manganese deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes manganese. This will remove any extra iron or nutrient salts that may be affected the uptake of manganese, it will help restore pH to the proper levels, and will supply the plant with any missing nutrients.

You are looking to avoid higher pH ranges, as this is where manganese deficiencies are most likely to occur.


Leaf Color:*
Pale Color Leaves
Yellow Leaves - New Growth
Yellow Leaves - Lower, older leaves
Yellowing Between Veins
Veins of Leaves Stay Green
Brown or Dark Spots
Mottling / Mosaic Pattern
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Lower Leaves / Older Growth Affected
Yellowing Between Veins
Veins of Leaves Stay Green
Spots
Mottling / Mosaic
Slow Growth
Abnormal Growth
Plant Symptoms:*
Slow Growth

Cont.

[MrG]

Manganese Deficiency

Problem: Leaves may become yellow in between the veins, with mottled brown spots on the affected leaves. These brown dead patches may spread and eventually kill the leaf. Leaves may also shred and fall apart.

Overall growth of the marijuana plant may be stunted. With a manganese deficiency, the yellowing will begin at the base of the leave and move outwards towards the tips.
*

Solution for Manganese Deficiency in Cannabis

Your plant may also exhibit signs of a manganese deficiency if the pH is too high, or if the plant is getting too much iron.


Please note: After a manganese deficiency is cleared up, the problem (brown spots and yellowing leaves) will stop spreading to other growth usually within a week. Please note that leaves which have been damaged by a manganese deficiency will probably not recover or turn green, so you want to pay attention to other growth for signs of recovery.

In soil, calcium is best absorbed by the roots in the 6.0 - 7.0 pH range (some growers recommend keeping the pH slightly lower, from 6.0 - 6.5, if you suspect a manganese deficiency in particular)
*
In hydro, calcium is best absorbed by the roots in the 5.5 - 5.8 pH range (in hydro, it's generally recommended to keep the pH between 5.5 - 6.5, but manganese specifically tends to be best absorbed below 5.8)
If you suspect your growing cannabis plant has a manganese deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes manganese. This will remove any extra iron or nutrient salts that may be affected the uptake of manganese, it will help restore pH to the proper levels, and will supply the plant with any missing nutrients.

You are looking to avoid higher pH ranges, as this is where manganese deficiencies are most likely to occur.


Leaf Color:*
Pale Color Leaves
Yellow Leaves - New Growth
Yellow Leaves - Lower, older leaves
Yellowing Between Veins
Veins of Leaves Stay Green
Brown or Dark Spots
Mottling / Mosaic Pattern
Leaf Symptoms:*
Upper Leaves / Newer Growth Affected
Lower Leaves / Older Growth Affected
Yellowing Between Veins
Veins of Leaves Stay Green
Spots
Mottling / Mosaic
Slow Growth
Abnormal Growth
Plant Symptoms:*
Slow Growth.

Cont.